Until recently, display devices have typically used cathode-ray tubes (CRTs). Presently, much effort is being expended to study and develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs), as a substitute for CRTs.
These flat panel displays have a light emitting layer or a light polarizing layer on at least one transparent substrate. Recently, an active matrix type flat panel display, where a plurality of thin film transistors (TFTs) are arranged in a matrix manner, has become widely used due to high resolution and high ability of displaying moving images.
The flat panel display includes multiple thin films. Accordingly, the flat panel display is fabricated through the repetition of a thin film-depositing process, a photolithography process and a thin film-etching process. Also, when a thin film pattern formed through such processes has defects such as an open circuit or a short circuit, a process for repairing the defects of the thin film pattern is conducted.
A thin film-treating process such as a depositing process, an etching process and a repairing process is conducted in a vacuum chamber for thin film-treating. The vacuum chamber has a vacuum condition area. However, large sized substrates are problematic for the vacuum chamber. In other words, as a size of the flat panel display recently has increased, a size of the chamber also increases in accordance to a size of the substrate. Accordingly, the space occupied by the vacuum chamber increases. Further, a large sized vacuum chamber is advantageous for treating a large area of a substrate but is disadvantageous for treating a small area of a substrate such as repairing a part of a substrate having defects.
To solve these problems, instead of the vacuum chamber requiring a large-sized vacuum condition area, a gas shield type thin film-treating apparatus for treating a part of a substrate having defects such as a short circuit or an open circuit has been suggested.
FIG. 1 is a cross-sectional view of a gas shield type thin film-treating apparatus according to the related art.
As shown in FIG. 1, a gas shield type thin film-treating apparatus uses laser-induced chemical vapor deposition. In other words, thin film treatment is conducted by photolysis using light to irradiate a part of a substrate 2 and a reaction gas supplied to the irradiated part of the substrate 2 under atmospheric pressure.
The gas shield type apparatus includes a stage 10 where the substrate 2 is placed, a gas shield 30 over the stage 10, and an energy source 50 over the gas shield 30.
The stage 10 moves up/down and left/right i.e., horizontally and vertically, by using an operating unit (not shown). The gas shield 30 has a retention space 32, which is open up and down, disposed at a center portion of the gas shield 30 corresponding to the energy source 50. The upper open portion of the retention space 32 is shielded by a transparent window 34. A laser beam “L” irradiates a part of the substrate 2 through the transparent window 34 and the retention space 32. A reaction gas supplied to the retention space 32 flows into the substrate 2. A plurality of exhaust grooves 38 are disposed at a rear surface of the gas shield 30 facing the substrate 2 to exhaust the residual reaction gas on the substrate 2. A gas exhaust path 40 is connected to the exhaust grooves 38 to exhaust the residual reaction gas outside. A gas supply path 36 is connected to the retention space 32 to supply the reaction gas. Both the energy source 50 and the gas shield 30 are fixed, and the laser beam “L” of the energy source is focused on a part of the substrate 2.
The substrate 2 is placed on the stage 10, and the stage 10 moves to align the energy source 50 and the gas shield 30 with the substrate 2. Then, the laser beam “L” from the energy source 50 is focused on the part of the substrate 2, and the reaction gas is supplied to the retention space 32 and flows into a surface of the substrate 2. The reaction gas is activated by the laser beam “L” at the focused part of the substrate 2, and thus a thin film pattern having a dot shape is formed. Then, the stage 10 moves with the energy source 50 and the gas shield 30 fixed. Accordingly, a repair line as a thin film pattern having a line shape is formed by continuing to form the dot-shape thin film pattern. Therefore, an open-circuited line pattern is repaired with the repair line. With the gas shield type apparatus, a zapping process, if necessary, is conducted prior to repairing the open-circuited line. In other words, density and intensity of the laser beam “L” are adjusted adequately and the laser beam “L” irradiates the substrate 2 without the reaction gas, and thus an insulating layer on the open-circuited line pattern is removed to expose the open-circuited portion of the line pattern. In a similar manner, a short-circuited line pattern is separated.
In the related art gas shield type apparatus, enough reaction gas is supplied to the focused part of the substrate 2 to conduct thin film treatment. However, since thin film treatment is conducted under atmospheric pressure, a large amount of reaction gas is wasted. Also, since the stage 10 moves to conduct thin film treatment, a sufficient amount of the reaction gas is sometimes not supplied to the focused part of the substrate 2.
FIG. 2 is a cross-sectional view illustrating a flow of a reaction gas on a substrate in the related art gas shield type thin film-treating apparatus.
As shown in FIG. 2, the reaction gas supplied to the substrate 2 through the retention space 32 flows, which is shown as a flowing line “G”, according to moving of the stage 10. In other words, friction between the reaction gas and the substrate 2 is generated due to moving of the substrate 2 to the right. Also, the exhaust grooves 38 exhausting the reaction gas move relative to the substrate 2. Accordingly, the reaction gas flows with the moving direction of the substrate 2 and is wasted. Therefore, sufficient reaction gas is not supplied to the focused part (focal point) “F” of the substrate 2 irradiated by the laser beam “L”.
Further, when a moving speed of the stage 10 increases, a flow of the reaction gas further increases. Accordingly, the reaction gas does not remain and flows away from the focused part “F” of the substrate 2. Therefore, reliability of thin film treatment is reduced.
As a result, a moving speed of the stage 10 is limited for thin film treatment, and thus productivity and efficiency of the apparatus are reduced.
Further, since the stage moves, the space occupied by the gas shield type apparatus increases as a size of the flat panel display recently has increased. Also, a heavy burden is imposed on the operating unit to move the large-sized stage 10.